Earlier quoted context omitted.
The market does not think. It is neither efficient nor rational. If the stock market is about the future, then how do you interpret Goldman Sachs' share price of $235 in November 2007? 1 year later it fell to $53. A company's share price will tell you nothing about the actual financial stability or future of the company.
This man is absolutely right. The stock market is rarely rational. This is exploited by value investors , like myself, who invest in companies that are undervalued for no reason.
Which tends to make the market more rational again.
But I agree that the market is not always rational, else there would never be a bubble.